Small angle x-ray scattering (SAXS) and its higher resolution counterpart wide angle x-ray scattering (WAXS) provide the global structural properties of biomolecules in solution. SAXS has flourished at Cornell, largely because of proximity to the Cornell High Energy Synchrotron Source (CHESS) which has raised awareness of the value of SAXS to structural biology. Cornell researchers not only use SAXS to measure structures, they develop and contribute new SAXS based methods to the research community. This application requests funds to purchase a laboratory source for small and wide angle x-ray scattering experiments. Recent improvements in the capabilities of lab sources now make them attractive for screening samples in advance of synchrotron time, and for developing or optimizing instrumentation for new SAXS based approaches. Researchers would no longer have to wait for allocated time at synchrotrons to acquire structures, screen samples or conditions for state-of-the art experiments that require painstaking preparation. Precious, short-lived samples, including protein-detergent complexes, or oxygen sensitive proteins could be screened as they are manufactured. The instrument will also push new fields forward, by allowing in depth exploration of instrumentation in new regimes for SAXS, such as cryo-SAXS. The machine will be housed in a dedicated laboratory on the first floor of the Physical Sciences Building at Cornell, directly adjacent to the labs of the major users. It will serve faculty in four departments, addressing a broad variety of research questions with a common theme of measuring structures and structural changes. In addition, it will serve as a development and educational resource for the (NIH funded) MacCHESS component of CHESS.